SketchUp is a 3D modeling software that is commonly used in the building industry by architects, interior designers, landscape architects, and other building engineers. Sefaira is a cloud-based computing software that is used for high performance building design. Sefaira also works as a plugin in SketchUp.
In this article, an overview of using both SketchUp and Sefaira as a performance-based design modelling for a building is explored. Here, a school study model was created in SketchUp and the energy modelling and daylight analysis of that building was analyzed in Sefaira.
The step by step process to create the school model shown in the image below is as follows:
- The measurements were taken from the drawing plan in AutoCAD and drawn in SketchUp.
- The layout of the model was extruded to a ceiling height of 3.96 m. This height is constant for the entire school.
- The window is 1.1 m from the floor and has a window height of 1.4 m.
- The model consists of concrete walls and clear float glass windows.
Upon creating the school model, the Sefaira plugin was launched. The Sefaira plugin will tag each plane’s surface as an entity by default. The user is then allowed to change any entity types to the desired entity type if it is wrongly tagged. All internal and external surfaces must be tagged to an entity type and can be displayed by activating the entity palette and then clicking on show entity types. Right clicking on an entity can allow the user to select and tag as the desired entity type. In the entity palette, the bullet point to the left of the entity can be clicked to isolate one or more entities at a time. This allows the user to ensure that all planes are tagged as the desired entity type. Surrounding buildings can also be constructed and tagged as shading.
The orientation of the building was then rotated accordingly and the building location input was added. Weather and climate data used for the analysis was based on the location assigned. The school study model is set in Kuala Lumpur, Malaysia and the ASHRAE 90.1 – 2013 metric unit was used.
With all the building geometry and inputs clearly defined, Sefaira can generate results of the building in real time by clicking on the update analysis tab. This enables the user to see the breakdown of energy consumption of the building in real time. For every subsequent change in model’s geometry, the update analysis tab will once again generate the results of the building.
Daylight Analysis
Sefaira uses two daylighting metrics for the model. Spatial Daylighting Autonomy, which describes how much space receives a satisfactory daylighting and Annual Sunlight Exposure, which describes how much of the space receives too much direct sunlight. When running the analysis, the model will generate the results with floor by floor analysis. However, our model has only one floor. The school has operating hours of 8am to 6pm and average occupancy for the whole year. The results are shown in the images below. The simulation was conducted with an overcast sky. The minimum illuminance is set to 300 lux, which is the minimum requirement for a school based on the Malaysian code of standards for energy efficiency and use of renewable energy for non-residential buildings, MS1525. This is measured 0.85 m from the floor plane as the ideal workspace height.
The average daylight factor shows the overall daylighting for the school. The average daylight factor based on the simulation is 1.96% with a zero uniformity ratio. The minimum daylight factor shows the lowest daylight in the area, excluding a perimeter zone around the walls. This is the worst-case value within the area. Figure 4 shows a room in the school to show the minimum point and uniformity ratio, where the minimum point is at 0.40%. Uniformity Ratio is the ratio of minimum daylight and average daylight. Typically, deeper rooms have a lower uniformity ratio since bright light is concentrated near the windows. A low uniformity value helps to expose such cases of uneven lighting in a space. In this case the result is 0.10, which shows that the room is receiving uneven lighting.
Energy Analysis
The energy analysis was taken based on the annual operational hours in the school. The result below shows the brief annual energy breakdown, and total energy consumption of the elements in the school.
The overall experience with Sefaira and SketchUp as a first-time user was positive as it was a fairly straightforward and user-friendly software. As the building industry progresses towards a sustainable future, the use of Sefaira can enable architects and engineers to incorporate sustainable design into the building easily. The metrics available in the Sefaira allow for the green building features such as passive and active design features to be included into the building at an early stage that will benefit the daylight and energy analysis when conducted later on.
